Earth Blog

California has a state rock, and some people want to get rid of it, reports this article in the New York Times. Is California losing its coolness or does it have a point?

California’s state rock is serpentinite. Not serpentine. Serpentine – (Mg,Fe)₃Si₂O₅(OH)₄ – is the name of the mineral group containing antigorite, chrysotile and lizardite.

Chrysotile is an asbestos mineral and that is the reason someone has decided serpentinite – a rock made up of mainly serpentines – should no longer be California’s state rock.

I like the discussion, for five reasons:

• First of all, I did not know that there are states with a state rock, so I am being educated. I like the idea, too, as it makes people more aware of geology and other earth sciences.
• Secondly, I think it’s remarkable to have serpentinite as your state rock.
• Thirdly, it may help educate non-geologists about rocks and asbestos and the various types of asbestos.
• Fourth, it points out that natural things can be harmful too – not just synthetics – and that natural equals chemical.
• It raises awareness for asbestos disease and the risks of working with asbestos. Safe handling is required.

As already mentioned, the asbestos mineral that can occur in serpentinite is chrysotile. Chrysotile is called white asbestos and is the most used type of asbestos. Serpentine crystals are leaf-like; in chrysotile, the sheets are rolled into long fibers.

Other asbestos minerals are part of the amphibole mineral group. Their general formula is A₂B₂(Si,Al)₈O₂₂(OH)₂. A is usually Mg, Fe, Ca and Na. B stands for Mg, divalent Fe, Al, and trivalent Fe. Amphiboles are inosilicates, which means that the oxygen-silicon tetrahedrons in it are linked in long chains, leading to elegant needle-like crystals.

The amphiboles include five asbestos minerals. Amosite (green, brown) and crocidolite (blue) are most used (after chrysotile). The remaining asbestos minerals – tremolite, actinolite and anthophyllite - are much less frequently used. Crocidolite is mainly mined in South Africa.

Tiger eye is a mix of quartz and crocidolite (or riebeckite, another amphibole), in which the crocidolite has been (partially) replaced by quartz. Below is an image of tiger eye. The remnants of crocidolite give it its pretty look. The rusty color is indeed the color of iron rust.

Jade can be a gem stone quality serpentinite.

Blue and brown asbestos pose the greatest health hazards – greater than that of the chrysotile occurring in serpentinite – but environmental conditions play an important role as the main risk of asbestos is associated with airborne asbestos dust.

The health hazards of asbestos are very different than those of substances like cyanide, carbon monoxide, osmium tetroxide or nitric acid.

About ten years ago, Dutch scientist Mirna Hensen concluded a prize-winning study assessing the safe limits and the impact of environmental conditions on the hazard of asbestos fibers in soil. In her experiments, notably the presence of even a small percentage of moisture in soil lowered the emission and hence the health risk of asbestos fibers considerably. Wind speed also played a large role.

Does this have anything to do with serpentinite as a natural rock? Yes, if you start sawing it and/or grinding it into dust, just for fun. Does having it as a state rock promote that? Frankly, I don’t know.

I do know this:

• If you drink water in great quantities, even water becomes toxic.
• Sports activities are generally seen as healthy, but cause many injuries too and even deaths.
• Florida is called the Sunshine State, and California sometimes is too. Overexposure to sunshine often leads to cancer and one in five Americans gets a form of skin cancer these days.

I have absolutely no worries about my tiger eye, nor about my serpentinite sample. I have no plans of doing anything with them other than looking at them occasionally, which is harmless. I no longer wear the tiger eye but that is because I simply have grown out of it and rarely wear pendants anyway.

I applaud asbestos disease awareness, and I do understand that this discussion heightens asbestos disease awareness. The focus of such discussions, however, should be on to limiting asbestos health risks in real life. Banning serpentinite as a state rock is a little bit like trying to make the sun illegal because it emits UV.

The above image is a photograph from 1913. It shows the fibrous nature of asbestos-containing rock from Québec under a polarisation microscope (the type of microscope earth scientists use). Magnification: 14 x, crossed nicolls.

PS
A special note to those with asbestos disease and their loved ones: I am not in any way trying to belittle your experiences and insights. I grew up witnessing three different types of cancer wreak havoc in three different people close to me. Lung cancer – one likely dust/tobacco-related – later claimed two other relatives.

I do not smoke and I rarely eat meat, but I have worked with all sorts of harmful substances, even osmium tetroxide, because I know how to handle them safely.